Mode of operating valves in steam-engines



UNITED STATES PATENT OFFICE.

GEORGE l'. WASHBURN, Ol" WORCESTER, MASSACHUSETTS.

MODE OF OPERATING VALVES IN STEAM-ENGINES.

Specification formingr part of Letters Patent No. 08,726, dated Januaryll, 1870.

To all whom it may concern:

lie itknown that LGEORGE I. WAsnBUnN, of Worcester, in the county ol`Worcester and State of Massachusetts, have invented certain new anduseful Improvements in Valve- Movemcnts i'or Steam and other Engines 5and that the following is a sutliciently full and ex act description ofmy said invention to enable one skilled in the art to which itappertauns to carry it into elect, reference being had to theaccompanying drawings, which are made part of this specification.

The primary object of my invention is to so actuate and control a valvethat when the motion ot' the steam or other Huid is to be reversed orchanged the valve will be caused to move instantaneously, withoutwait-ing for the accumulation of pressure, and without a possibility ofit resting on any dead-point.

To this end I operate the valve in the following manner: First, loadingit so that it cannot move; second, applying pressure in the direction inwhich the valve is to move, insucient to overcome the load referred to,but fully suiicient to move the valve when released third, when the timecomes to move the valve and reverse the steam upon the main piston, (oranyother fluid which is to be controlled,) removing or balancing thepressure first referred to, so that the pressure secondly referred towill throw the valve instantaneously and without fail.

My invention, as above set forth, may be embodied in various ways, ofwhich I shall proceed todescribe four, all involving the same principlesof operation, and each susceptible of various modifications.

In the drawings, Figure 1 represents a lougitudinal section of asteam-cylinder and piston, with the valve mechanism placed inside thepiston, and adapted tobemoved by steampressure. Fig. 2 is a transversesection of the same, in the plane indicated by the line a: fr, Fig. l.Fig.3 shows a transverse section ot' a. part thereof', at y y, Fig. 1.Fig. 4 is a longitudinal section, showing a similar valve located withinthe piston, and adapted to be thrown by the agency ot springs. Fig. 5isa longitudinal section, representing the valve mechanism ou theoutside of the nia-iu cylinder, and operated by the pressure ol' steam.

Fig. 6 is a transverse section at z z, Fig. 5. Fig. 7 represents, inelevation, the adjacent. ends ol a. steanrcylindcr and ptunp-cylilulcr,with a pis-toured common to both, and an nrln by which the steam valveis thrown` through the medium of springs, as hereinal ter described.

Lilie letters ol' reference indicate like parts in all the figures.

The steam-cylinder A, with its heads a a, may be of any common orsuitable const-ruction.

lu the form ol' the invention represented in Figs. l, 2, and 3, l employa hollow piston, B, the interior of which is divided into four chambers,ol' which two, b b, which are opposite to each other, are always incommunication with the steam-supply port S, and the other two, bJ b,which are also opposite each other, are in constant communication withthe exhaust-port E.

In order to maintain the communication ol' the chamber bl with thesteam-port S at all parts of the stroke, I provide a slot, s, Figs. land 2, the length of which exceeds that of the stroke of the piston.

The chamber b3 communicates with the exhaust-port E through a similarlongitudinal slot, e.

In order to balance the pressure on the opposite sides of the piston,the chamber b communicates with the chamber b, through an open passage,b5, Figs. 1 2, and3; the chamber b' communicates with the chamber b byone or more similar passages, indicated by dotted lines in Fig. 2; andslots s and c* are formed in the walls of the piston, corresponding inarea, and diametrically opposite in position, to the slots s and e,respectively.

The steam is introduced to and withdrawn from the ends of the cylinderalternately through ports P' I, whose inner ends are made to communicatewith the steam and exhaust chambers alternately by a valve, V,consisting of n hollow cylinder, with three parallel grooves, 1J v v,extending around its periphery. The widthof each of thesegrooveslongitudinally oi' the valve is slightly greater than the length ol thestroke or throw of' the valve` within the pistou.

The central groove r communicates con stanti)` with the exhaust. throughthe ports e b5 e, and alternately with the ports P1 P2 of the piston.

The grooves t" v2 communicate constantly with the steam-chamber b',through the ports s s2, and alternately with one or other ot the portsl1 l, one of the grooves v n2 being used for each of the ports Il l, soas to introducc the steam-pressure to the said ports alternately.

Within the cylindrical valve V is a plug or rod, C, which projects outthrough the ends of the valve and ol' the piston, and is provided at itslongitudinal center with a flange or collar, c, upon which the valveworks steam-tight, and which constitutes an abutment tor the steam orother motor to act against, as will presently be explained.

Mv description thus far applies to the form of the invention illustratedin liig. 4, as well as that shown in Figs. l, 2, aud 3. In theillustration given in Fig. 4, springs F l12 are employed to impart theendwise throw to the valve, which, in the illustration shown in Figs. l,2, and 3, is el'ected by steam-pressure within the hollowl valve..

To ad mitthesteam within it, the hollow valve V, Figs. 1, 2, and 3, isconstructed with ports s3 s, communicating with the steanrgrooves 'vlv2, respectively, the said ports being located so far apart that neitherof them may pass or reach the central lange orcollar c ot' ithestationary plug C as the valve moves. Two additional flanges or collars,c c2, on the stationary plug C, serve to close one or other of the portssas* as the valve moves, the arrangement of the said ports and flangesbeing such that one of the ports will be closed as the other is opened,and vice versa. The steamchambers at the respective ends of the hollowvalve communicate, also, with the exhaustgroove 'v through passages e3e4, which are, in ike manner, so control ed by the stationary tanges orcollars c o that one only of them is open at a time, and the parts c* cs3 s* e3 e* are so constructed and relatively arranged that, while thesteam-port si' at one end ot' the valve is open, the exhaust-port e* atthe other end will be'open, and s* and e closed; but while thesteam-port s* is open, the exhaustpassage e will be open and s3 and eclosed.

As the flanges or collars cl c2 are employed only to open and closesteam inlets and outlets' to and from the interior of the valve, and notas an abutment for the steam in moving the valve, the said flanges orcollars are perforated, as shown in Figs. l aud 3, to allow the steam topass freely through them, and equalize the pressure on their oppositesides. Additional steamports 8 85 are located near the ends of thevalve-chest, so that the valve will close one of them at each extremityof its stroke, but in its intermediate position will be subjected to abalanced pressure of steam upon its ends. G represents the pistou-rod.

Operation: The drawings represent the pis ton at the termination ot itsdownward stroke, with the valve reversed, so as to cause the upwardmovement of the piston, which will be el'ected by the pressure of steamadmitted through the passages S s s2 o" P2 to the lower end of thecylinder'. At the same time, the pressure of steam admitted through theport s into the valve-chest causes the valve to move upward with thepiston, this ett'ect being assisted by the pressure of steam admittedthrough the port s3 to the upper end of the iuterior of the valve, andacting against the stationary abutment c, the lower end ofthe inteA riorot' the vulve being' in communication with the exhaust through thepassage et.

The upward motion of the valve soon admits steam-pressure into the lowerend ofthe valve V, hy uncovering the port- .5" and closing the passagee* by the collar o, and at the same time the steam-port s3 is closed bythe collar c1 and the u i er end of the interior ot i il the valve isexhausted through the passage e3. A downward pressure is thus applied tothe interior ot' the valve, but this'does not immediately move thevalve, because it is overhalanced by pressure upon the exterior of thelower end of the valve, the area of which is greater than that of theinterior surface upon lwhich thc downward pressure is exerted.

Before the piston completes its upward stroke the lower end of the valvecomes in contact with the stationary collar c, The motion of the valvebeing thus arrested, the continued movement of the pistou B immediatelyuncovers-the port s", admitting steam to the upper end of thevalve-chest, the downward pressure of which upon the valve balances theupward pressure against the lower end of the valve, and permits thepressure within the valve to throw the latter down against the lower endB2 of the piston, so that the upper end of the cylinder will receivesteam through the passages S s s 'v P1, and the lower end will beexhausted through 1*"2 o ez b5 e VE. The' downward stroke lis then made,and the valve again reversed in the manner already described in relationtothe upward stroke. `In each case the entire steam-pressure which is tomove tlievalve is applied to it before the time comes for it to move;but is overbalanced by a greater pressure until the proper moment for itto more, when the load being either counterbalanced or removed, theentire pressure of' the steam acts to throw the valve instantaneously.

I am thus enabled to control the pistou with absolute certainty, howeverrapid its m0- tion, and I avoid all the diieulty commonly experiencedwith valvcs operated by steam in waiting i'or the passage of steam orthe accumulation of pressure.

ln theillustratiou given in Fig. 4 the springs Fl F2 within the hollowvalve perform the same functions as the pressure of steam within thevalve in the arrangement already described. Fig. 4 shows the position olthe parts at the instant that the valve has been reversed and thc pistonhas begun its upward stroke. As the piston descended, the valve whichrested against the lower head B'L under pressure ot' steam enteringthrough the port S5, compressed the spring Fl nntil the resistance 0fthe latter overcame the steam-pressure on the valve. The continuedmotion ol' the piston then uncovered the port s6, permit ting steam toenter the lower part ol the valvecbest and exert an upward pressureagainst the lower end of the valve, which, balancing the downwardpressure upon the upper end, permits the spring h" to throw the valveinstantaneously to the position shown in the drawing, so that steam isadmitted to the lower cnd ol the cylinder through the passages s2 122l", and exhausted from the upper end through P, n, e2, b5, and c. lhevalve V then rises with the piston until the resistance ol the springF'l overcomes the pressure of steam admitted through the port s, whenthe port S5 is again uncovered, admitting a balancing pressure to theupper end of the valvechest, when the valve is again instantaneouslyreversed by the action of the spring F2. Steam is thus admitted to theupper end of the cyliudcr, through the passages 'vl and Pl, and thesteam in the lower end exhausted through 1E2 'v e2 and their connectionsbefore named. In both these forms of the invention I prefer to provideor permit a slight leak for the steam where the plug U passes throughthe pistonheads, so that any steam imprisoned in either end of thevalve-chest may escape into the exhaust as soon as the valve isreversed; but this leak is not so great as to destroy the cushioningeffect on the valve, which is caused by locating the portsssat a littledistance from the ends uf the valvechest.

Figs. 5 and 6 illustrate the invention applied under a modified formthatis to say, with the valve working in a stationaryr steamchest, externalto the main cylinder and actuated by steam-pressure under control of acentral plug, C, which is moved near the termination of each stroke ofthe pist/0u B by an arm, H, attached to the piston-rod G, and actingagainst tappets c3 c upon the rod C,'to which the plug C is attached.

Fig. 5 represents the piston approaching the downward termination of itsstroke, the arm H having already come in contact with the tappet c, soas to force `down the plug C and valve V until the steam-port $5 isopened so as to admit steam to the upper end of the valve-chest` thedownward pressure of which upon the upper end of the valve balances theupward pressure ol'thestcam admitted through the port s. Thel externalpressure on the valve heilig thus balanced, the valve is instantaneouslythrown down by pressure of steam already admitted to the lower part ofthe interior of the valve through the port c. B v this motion ot' thevalve the passage l"z is plared in communication with steam through andthe passage l" in com.

the groove vl,

the exhaust through tinmunication with groove v, and thus the upwardstroke ol' the piston is produced, the valve and all its accessoriesremaining stationary` until the arm ll, striking the tappet. c, movesthe plug U upward. 'lhc port s3 is thus uncovcrcd, admittingr steamwithin the upper end of the valve. which steam, acting against thecollar c as au abutnunt, and passing freely through the perforatedcollarc, exerts an upward pressure upon the valve, lult not Sullicientto overcome the external pressure of steam admitted through the port sito the upper end of the valve-chest. The valve. therefore, does not moveuntil the contact of the collar c* with its upper end raises itsuicicntly to uncover the port s", when the external pressure, beingagain balanced, the internal pressure in the upper end throws the valveup, placing the steam-groove rvz in communication with the passage l",and the eshaust-groove U with the passage P2, and thus imparting thcdownward stroke to the`piston.

[n the illustration given in Fig. 7, springs l Iz are interposed betweenthe arm B and tappets c3 c on the valve-rod C', and, instead ofemploying steam-pressure to load the valve until the time comes to moveit, the rod is locked by catches J J2 engaging alternately with thetappets ca and c. In Fig. 7 the piston-rod is represented as movingl'rom right to left. The arm H, carrying the spring l before it,compresses it with considerable force against the tappet c until thesaid arm, in passing under the inclined face of the catch J', raises it,releasing the tappct c, and causing the valve to be throwninstantaneously by the action of the spring I. When used in a steam-pumpoperated by exhaust-steam, or any other steam having very low pressure,the arrangement last described has this peculiar value, that the wholearea of the main piston is made available for moving the valve th roughthe medium of the springs, whereas, if the valve be moved by directpressure of steam, its area must be large or the propelling forceapplied to it proportionately small. A balanced valve is preferable forthis purpose, but any form of valve may be used.

My principle ol' loading or locking the valve against an elasticpressure, which will throw it instantaneously when the resistance isremoved or counterbalanced, may be embodied in any ofthe forms abovedescribed, or in various others which will suggest themselves to theskilled mechanic or engineer. For example, the plug C may be as long asthe cylinder, as in the present illustration, or it may be shorter. Thedevice will work equally well in a. cylinder ot' any length. Tho plug,projecting from the piston in tbc direction in which the latter ismoving, will not act upon the valve until its own motion is arrested bycontact willi the c vliiulcr-head, and then it will check the valve, soas lo canse the latter to he thrown by internal pressure, as explained.Again, the plug may be f astened to the cylinder at one end, instead ofresting against both heads of' the cylinder; and aga-in, the inventionmay be used with a, stationary piston :ind n moving cylinder.

The invention is applicable to steam engines, steam-pumps, wfltel motorsor meters, or any other purpose where :t valve is required to controlthe movement of' a piston or its equivalent.

In the common mode of operating valves by steam, they receive thepressure only when their motion should take place, and, unless the steamacts instantly, thel mein piston is liable to strike the cylinder-head.Again, as the valve starts as soon as the pressure upon it equals itsown resistance, the vnlvc will not generally act under fullboiler-pressure. Nows as (under the ordinary arrangement) the steamwhich moves the valve is immediately eut off from it, the valve isliable to move over only a part of its stroke before its Steam is cutoff. My valve is subjected to full boiler-pressure before it is allowedto move, and this pressure remains on it during a. part of the returnstroke of the main piston. Hence, no valvemotion within my knowledge,except when a connection is made with e belance-wheel, can

GEO. I. WAS HBURN.

Witnesses:

EDWARD MELLEN, WM. S. DAVIS.

